Casing perforator



May 10, 1938.

E. HARR ET AL CASING PERFORATOR Filed Nov. 11, 1935 FIG.

FIG. 5

my flw m w 5% m4 ATTORNEY.

Patented May 10, 1938 UNITED STATES PATENT OFFICE CASING PERFORATORApplication November 11, 1935, Serial No. 49,208

2 Claims.

This invention relates to perforators for piercing holes in casing, suchas that ordinarily employed in oil wells, which are adapted foractuation with both standard and rotary drilling tools, by thereciprocation of a drilling line, pipe, tubin; or the like to which thedevice is connected in operation.

The perforation of well casing by the forcible projection of a pointedprong therethrough is well known. A principal difiiculty of many of suchprior art devices is that they provide for only a single perforatingelement, and no means are included for offsetting the unbalanced effectof the single thrust. As a result, the perforator will tend to tilt,straining the joints and causing friction between distortedreciprocating parts, which prevents efficient operation and restrictsthe useful life thereof.-

A principal object of the present invention is to provide a deviceadapted to simultaneously perforate a casing at two diametricallyopposite points and to thus balance the pressure exerted through thebody of the perforator, which will substantially maintain the centraldisposition thereof relative to the casing, and preserve the mosteifective angle of thrust ofthe perforating members with the casing wallduring operation of the tool.

Another object is to provide a device embodying perforating elements ofa suflicient length to perforate the walls of several concentric tubingsor casings in which the device may be operated, said perforatingelements being curved to follow the line of thrust of their points andprevent dissipation of pressure exerted thereon by excessive friction ofthe shanks of the elements in the perforated holes.

Still another object is the provision of a device embodying durabilityofconstruction and operation, ease of assembly, surety of action, andcapable of most efficiently utilizing the force of the downward thruston the reciprocating head of my invention.

Other objects and corresponding advantages will be apparent from anexamination of the following description and the accompanying drawingwhich shows one embodiment of our said invention, in which-- i Fig. 1 isa longitudinal view in section and elevation of my invention inelongated position with the perforating members withdrawn into the body;

Fig. 2 is a longitudinal view in section and elevation taken at rightangles to Fig. 1 on line 2-2 thereof;

(Cl. Hi l-0.4)

Figs. 3, 4, 5, and 6 are transverse sections on correspondingly-numberedlines of Fig. 1;

Fig. 7 is an elevation illustrating in dotted lines the relativeposition of the inner parts with the perforating members extended.

Referring more particularly to the drawing, the numerals of which referto similar parts throughout the several views, In designates the upperhead of my invention which may be secured in rotary drilled wells bymeans of a pin II to a drill pipe or, in wells drilled by the standardmethod, to a wire line, by means of sinker bars and jars, which will beobvious to those of skill in this art. Opposite sides of a lower portionof the head are cut away to provide a flat mandrel 12 for its slidingreciprocation within the body l3 of the device, hereinafter described indetail.

The body I3 is provided on its lower end with a pin 14 for attachment toa tubing section, (not shown) by means of coupling l5, on which ismounted downdrive spear mechanism for releasably supporting the body ofthe perforator against the downward movement, and permitting therelative reciprocation of the head l0 and associated parts therewith.The spear mechanism, being well known in the art, and not forming anypart of the present invention, is not illustrated or further described.

The body I3 is preferably constructed in two longitudinal sections l6and IT to facilitate assembly, each comprising a half circular lowerportion [8 so as to form a round tool when secured to its counterpart bythe coupling l5 into which the assembled body is threaded as abovenoted. a

The upper inside portion of both sections are cut away to form faces l9between which mandrel I2 is adapted to slide. The mandrel is preventedfrom being withdrawn. from the body by oppositely-disposed hooks 20 and2| integrally formed with the upper ends of sections l6 and ll, havingfiat sides perpendicular to the plane of faces IS. A slot 22 is formedin head IB into which the hooks 20 and 2! extend from opposite sideswhen the lower body is assembled on mandrel l2. The lower limit of slot22 adjacent mandrel I2 is curved to correspond with the contour of thehooks on which the body of the perforator is suspended duringpositioning of the spear mechanism.

A stud 23 in the center of the fiat side of hooks 20 is provided toextend into a correspondingly shaped hole 24 in the other hook 21, whichprevents separation of the hooks or of the sections I6 and i! when inposition between the walls of slot 22. In assembling the body sectionsl6 and I1, one of the hooks is extended through slot 22 so as toprotrude outwardly from the other side of the head. The other hook isthen placed against the first in operative relationship, with stud 23engaged in hole 24. The oppositely-extending hooks are then moved intovertical alignment with slot 22, which endless body sections [6 and I!to assume parallel positions on opposite sides of the body and theirrelative contact at their lower ends for attachment of coupling Hi. Whenthe coupling has been threaded over the lower end of the body the hooksthereof are maintained in slot 22 against lateral displacement by stud23 and the walls of slot 22.

Perforating members hereinafter described in detail are connected tohead 10 by means of connecting arms 25 pivoted to opposite sides ofmandrel l2 in a bearing 26 provided therefor. Bearing 26 comprises acircular disk 21 machined in the lower end of the mandrel and having ahole 28 through its center. Downwardly-directed semi-circular shoulders29 overhang the disk 21 on each side, which the curved ends ofconnecting arms 25 are adapted to contact to receive the brunt of thedownward thrust of head H]. A pin 35 formed adjacent the ends of thearms 25 engages in hole 28 and is reinforced at its upper periphery towithstand the force necessarily exerted in extracting and returning theperforating members from the punctured easing into the perforator body.

The connecting arms 25 are curved to slidably fit in the upper portionof a guide channel 3| provided on the inside of each section, whichchannels extend to opposite sides of the assembled body. The upperportion of each channel is enlarged and forms a circular shoulder 32 atthe lower end of the enlargement against which the connecting arms mayabut to limit the downward movement of the upper head. Distribution ofthe strain of the abutment of upper head and associated elements withthe lower body is accomplished by proportioning the device to permitcontact of the hooks 2B and 2i with the upper end of slot 22 in head H3simultaneously with the engagement of connecting arms 25 with therespective shoulders 28 in channels 3E.

At the end of each connecting arm 25 a bearing 33 is provided comprisinga laterally-extending pin 34. On each of pins 34 a perforating member 35is pivotally suspended. Each member receives its downward thrust, from ashoulder 36 formed in the lower end of arms 25 conforming to the shapeof the round end of the members 35.

The perforating members adaptable for use in the present embodiment arerectangular in crosssection, with the bezel of the point entirely on theupper end. It should be remembered, however, that the perforatingmembers may be of any shape and associated parts altered to conformtherewith.

To most effectively utilize the downward pressure on the reciprocatinghead, the perforating members should strike the casing at right angles,which may be accomplished by varying in specific embodiments, the curveof arms 25 and perforating members, relative to the length of theirthrust to the casing wall. The direction of pressure on the perforatingmembers may be accordingly changed, for maximum efficiency, to complywith the curve of arms 25 and the perforators 35 by the positioning ofpins 34 on the perforating members.

It will be obvious to those of skill in this art that changes may bemade in the relative size, proportion, number, and position of thevarious parts hereof, without departing from the spirit of ourinvention.

Having described our invention, we claim:

1. In a casing perforator, a bifurcated body, a reciprocating headslidably extending between the bifurcations of said body, having a slotlongitudinally disposed therethrough, hooks secured to the end of thebifurcations extending from opposite sides into the slot in said head soas to abut against the upper limit of the slot, or suspend the body onthe lower limit thereof at respective ends of the reciprocating strokeof said head, and perforating members connected to said head.

2. In a casing perforator, a reciprocating head having a longitudinalslot therein, a body comprising two longitudinal sections, each sectionof which body having a hook at its upper end adapted to extend into saidslot to engage the lower end thereof upon elevation of said head, aconnecting arm pivotally attached to the lower end of said head, aperforating member pivoted to the lower end of said connecting arm, andmeans in said body to guide said perforating member laterally relativethereto.

HERMAN E. HARR. HAROLD COLWELL.

